The invention is directed to a method and to an apparatus for tensile testing of spliced fibers in fiber splicing devices which clamps the fibers on each side of the splice in fastening means.
Two methods are known for connecting the optical fibers being increasingly utilized in optical communications technology: first, gluing fiber end faces into pre-fabricated and standardized plugs and, second, splicing fibers with prepared fiber end faces to form a single fiber. When splicing the fibers in fiber splicing devices, two fibers with prepared end face are secured on two carriages that can then be moved with adjustment devices so that the fiber end faces can be aligned well relative to one another. After the adjustment, the two fiber ends are then generally thermally welded. For quality control of a splice, both the additional attenuation caused by the splice as well as the tensile stress withstood by the splice are checked.
The publication xe2x80x9cThermische LWL-Spleixcex2technik setzt such durchxe2x80x9d (V. Riech, Telcom Report 18, (1995), No. 3, pages 136 through 139) discloses a splicing device wherein a finished splice can be tested for tensile strength while it is still in the device (page 138, third column, second paragraph). The splice is thereby loaded with an integrated restoring spring of a carriage having a fixed tensile testing stress dependent on the restoring force of the restoring spring. The tensile testing stress is permanently set when assembling the fiber splicing device and can no longer be subsequently modified, this being disadvantageous when splicing different fiber types (single-wave or multi-wave fibers, stepped index over gradient fibers) for different applications. Moreover, the tensile stress acting on the splice depends on the insertion of the fiber, is thus dependent on the user and is not suitable for checking for standardized tensile testing stresses.
The present invention is based on the object of developing a method for tensile testing in fiber splicing devices, whereby the user himself preselects the tensile testing stress dependent on the fiber type to be spliced, and whereby the tensile testing stress is independent of the insertion of the fiber.
The object is inventively achieved by a method comprising the steps of clamping a fiber on one side of the splice in a first fastening means on a carriage and clamping the other fiber in a second fastening means, moving the carriage by an adjustment means opposite to a spring, controlling the operation of the adjustment means, measuring the tensile stress applied to the splice as the carriage moves away from said second fastening means, and moving the carriage until the tensile stress reaches a predetermined value.
As a result of the inventive method, the user of a fiber splicing device is provided with the possibility of setting the tensile testing stress as he deems fit and potentially according to different standards for different fiber types, this being advantageous particularly when splicing different fiber types with the same fiber splicing device.
Further, the inventive method is distinguished by higher position compared to the method known from the prior art with the restoring spring. Over and above this, it is no longer necessary to manually set the restoring force of the spring when a fiber splicing device is placed into operation.
For example, strain gauges or piezo-actuators secured to the carriage can be utilized for measuring the tensile stress acting on the fiber splice. In a preferred embodiment, a piezo-actuator is co-employed for measurement that is already present in the fiber splicing device for adjusting the fiber sub-sections before splicing.
The invention is explained in greater detail with reference to an exemplary embodiment shown in the drawing.